Data as of: DVSA MOT results to 2025
Ajs 18S vs Suzuki GSF600
The Ajs 18S passes its MOT first time more often than the Suzuki GSF600: 92.8% vs 77.3%, a 15.5-point lead.
MOT reliability, side by side
| Metric | Ajs 18S | Suzuki GSF600 |
|---|---|---|
| First-time pass rate | 92.8% | 77.3% |
| Outright fail rate | 3.0% | 14.2% |
| Engine size | 500cc | 599cc |
| Rank among all models | #330 of 5428 | #4013 of 5428 |
| Median miles at test | 14,829 | 21,080 |
| MOT tests analysed | 598 | 143,023 |
| Most common failure | lighting and signalling | brakes |
First-time outcomes on normal tests, 2005–2025. "Most common failure" is the component group with the most recorded defects on failed tests. Read pass rates against test counts: a smaller sample is noisier. Source: DVSA anonymised MOT results.
What fails, side by side
| Component | Ajs 18S | Suzuki GSF600 |
|---|---|---|
| Lights & signalling | 1.8% | 6.7% |
| Brakes | 0.5% | 6.1% |
| Steering & suspension | 1.2% | 3.6% |
| Tyres & wheels | 0% | 3.3% |
| Structure & body | 0.2% | 1.5% |
| Drive system | 0.2% | 1.4% |
| Fuel & exhaust | 0.2% | 1.2% |
A test that fails on two components counts once in each. Component links go to the bikes most likely to fail on it.
Pass rate by test year
| Test year | Ajs 18S | Suzuki GSF600 |
|---|---|---|
| 2006 | 95.6% | 81.8% |
| 2007 | 97.5% | 80.0% |
| 2008 | 95.8% | 78.4% |
| 2009 | 88.2% | 75.8% |
| 2010 | 88.6% | 75.8% |
| 2011 | 89.6% | 76.1% |
| 2012 | 93.3% | 75.9% |
Each year mixes bikes of different ages, so a fleet that is getting older tends to slip.
Pass rate by mileage
| Mileage | Ajs 18S | Suzuki GSF600 |
|---|---|---|
| 0k-10k miles | 93.2% | 86.8% |
| 10k-20k miles | 97.2% | 80.1% |
| 20k-30k miles | 90.5% | 75.2% |
| 30k-40k miles | 88.6% | 71.3% |
| 40k-50k miles | 92.6% | 69.4% |
| 50k-60k miles | 84.4% | 68.3% |
Bands with fewer than 30 tests for either bike are left out.
Ajs 18S vs Suzuki GSF600 FAQ
Which is more reliable, the Ajs 18S or the Suzuki GSF600?
The Ajs 18S passes its MOT first time more often than the Suzuki GSF600: 92.8% vs 77.3%, a 15.5-point lead. An MOT checks roadworthiness items, not engine or gearbox internals.
What does the Ajs 18S fail its MOT on most?
Lights & signalling: 1.8% of Ajs 18S MOT tests failed on it, then steering & suspension (1.2%).
What does the Suzuki GSF600 fail its MOT on most?
Lights & signalling: 6.7% of Suzuki GSF600 MOT tests failed on it, then brakes (6.1%).
Which holds up better at high mileage, the Ajs 18S or the Suzuki GSF600?
At 50k-60k miles the Ajs 18S passes first time more often: 84.4% for the Ajs 18S vs 68.3% for the Suzuki GSF600.
See each bike's full report (trend, mileage curve, failure breakdown and rivals) on its own page.